April 7, 2011
09:00 AM (EDT)

News Release Number: STScI-2011-10

NASA Telescopes Join Forces to Observe Unprecedented Explosion

April 7, 2011: NASA's Swift satellite, Hubble Space Telescope, and Chandra X-ray
Observatory have teamed up to study one of the most puzzling
cosmic blasts ever observed. More than a week later, high-energy radiation continues to brighten and fade from its
location. Astronomers say they have never seen such a bright,
variable, high-energy, long-lasting burst before. Usually,
gamma-ray bursts mark the destruction of a massive star, and
flaring emission from these events never lasts more than a
few hours.

On Monday, March 28, 2011, the Swift satellite's Burst Alert
Telescope discovered the source in the constellation Draco when
it erupted with the first in a series of powerful blasts. Swift
determined a position for the explosion, which is now cataloged
as gamma-ray burst (GRB) 110328A, and informed astronomers worldwide.
As dozens of telescopes turned to the spot, astronomers quickly
noticed a small, distant galaxy very near the Swift position. A deep
image, taken by Hubble on Monday, April 4, 2011, pinpointed the source
of the explosion at the center of this galaxy, which lies 3.8 billion
light-years away from Earth. That same day, astronomers used NASA's
Chandra X-ray Observatory to make a four-hour-long exposure of the
puzzling source. The image, which locates the X-ray object 10 times
more precisely than Swift, shows that the source lies at the center
of the galaxy Hubble imaged.
Astronomers previously have detected stars disrupted by supermassive
black holes, but none have shown the X-ray brightness and variability
seen in GRB 110328A. The source has
undergone numerous flares. Since Sunday,
April 3, it has brightened by more than five times. Although research
is ongoing, astronomers feel the unusual blast likely arose when a star
wandered too close to its galaxy's central black hole. Intense tidal
forces tore the star apart, and the infalling gas continues to stream
toward the hole. According to this model, the spinning black hole formed
an outflowing jet along its rotational axis. A powerful blast of X-rays
and gamma rays is seen if this jet is pointed in our direction.
Hubble observations of GRB 110328A's host galaxy were taken with
the Wide Field Camera 3 in visible and near-infrared light. This
Hubble image of the galaxy was taken in visible light. Astronomers
plan additional Hubble observations to see if the galaxy's core changes
brightness.